To converts text files between DOS and Unix formats you need to use special utility called dos2unix. DOS text files traditionally have carriage return and line feed pairs as their newline characters while Unix text files have the line feed as their newline character.

dos2unix (also known as fromdos) – converts text files from the DOS format to the Unix
format
unix2dos (also known as todos) – converts text files from the Unix format to the DOS format.
sed – You can use sed command for same purpose
tr command
Perl one liner
Task: Convert DOS file to UNIX format

Type the following command to convert file called myfile.txt:
$ dos2unix myfile.txt

However above command will not make a backup of original file myfile.txt. To make a backup of original file. The original file is renamed with the original filename and a .bak extension. Type the following command:
$ dos2unix -b myfile.txt